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Herein, we present the effect of electron-beam irradiation (EBI) on the gas-sensing properties of Pd-functionalized reduced graphene oxide (RGO). Scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the synthesized products. The samples were irradiated using electron beams at doses of 0 (Pd-RGO-0), 100 (Pd-RGO-100), and 500 kGy (Pd-RGO-500), and the NO2 gas-sensing properties were investigated. It was found that irradiation by electron beams has a critical effect on the gas-sensing properties of the samples, and the Pd-RGO-500 sensor showed the highest response to NO2 gas. In particular, the response of the unirradiated sensor and the sensor irradiated at doses of 100 and 500 kGy to 10 ppm NO2 were 1.027, 1.045, and 1.047, respectively. The response times of Pd-RGO-0, Pd-RGO-100, and Pd-RGO-500 to 10 ppm NO2 gas were 389, 335, and 345 s, respectively. The corresponding recovery times for these sensors were 808, 766, and 816 s, respectively. The increased numbers of oxygen functional groups and high-energy defects were the main reasons for the increased gas response. This study will eventually lead to increased performance levels of RGO-based sensors that use EBI, as this technology can introduce changes into materials in a non-contact, clean, and powerful manner.

We report the room-temperature sensing characteristics of Si nanowires (NWs) fabricated from p-Si wafers by a metal-assisted chemical etching method, which is a facile and low-cost method. X-ray diffraction was used to the the study crystallinity and phase formation of Si NWs, and product morphology was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After confirmation of Si NW formation via the SEM and TEM micrographs, sensing tests were carried out at room temperature, and it was found that the Si NW sensor prepared from Si wafers with a resistivity of 0.001–0.003 Ω.cm had the highest response to NO2 gas (Rg/Ra = 1.86 for 50 ppm NO2), with a fast response (15 s) and recovery (30 s) time. Furthermore, the sensor responses to SO2, toluene, benzene, H2, and ethanol were nearly negligible, demonstrating the excellent selectivity to NO2 gas. The gas-sensing mechanism is discussed in detail. The present sensor can operate at room temperature, and is compatible with the microelectronic fabrication process, demonstrating its promise for next-generation Si-based electronics fused with functional chemical sensors. [ABSTRACT FROM AUTHOR]